Java Data Type How to - Format a measurement into engineering units

Question

We would like to know how to format a measurement into engineering units.
Answer

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
// w ww. j  av a  2 s . c o m
public class Main{
  public static void main(String[] args) {
      Measurement dist = new Measurement(1337,"m"); // should be 1.337Km
      Measurement freq = new Measurement(12345678,"hz"); // should be 12.3Mhz
      Measurement tiny = new Measurement(0.00034,"m"); // should be 0.34mm

      System.out.println(dist);
      System.out.println(freq);
      System.out.println(tiny);

  }
}
class Measurement {
    static Map<Integer,String> prefixes;
    static {
        Map<Integer,String> tempPrefixes = new HashMap<Integer,String>();
        tempPrefixes.put(0,"");
        tempPrefixes.put(3,"k");
        tempPrefixes.put(6,"M");
        tempPrefixes.put(9,"G");
        tempPrefixes.put(12,"T");
        tempPrefixes.put(-3,"m");
        tempPrefixes.put(-6,"u");
        prefixes = Collections.unmodifiableMap(tempPrefixes);
    }

    String type;
    double value;

    public Measurement(double value, String type) {
        this.value = value;
        this.type = type;
    }

    public String toString() {
        double tval = value;
        int order = 0;
        while(tval > 1000.0) {
            tval /= 1000.0;
            order += 3;
        }
        while(tval < 1.0) {
            tval *= 1000.0;
            order -= 3;
        }
        return tval + prefixes.get(order) + type;
    }
}